FIG. 5.

Neutralization with HIV-1-positive human sera. A MAGI-CCR5 cell-based, single-cycle infection assay was performed as described in Materials and Methods, to test the neutralization sensitivity of VH-rBORI, VH-rB15, and VH-rV1V2 recombinant viruses (93) either in the presence of a 1/10 dilution of NHS or in the presence of increasing dilutions of serum from four HIV-1-infected individuals. Results were calculated as percentage of infection with respect to the extent observed with virus plus NHS, and the values shown represent the average of two to three independent experiments.